Grape Cutting Propagation with a Heat Mat

In the spring of 2012, I propagated grape vines using the following method.
1. A large Styrofoam cooler with drain holes (Omaha Steak cooler)
2. A Seed Heat Mat (brand unknown - black with light green writing)
3. 50% Perlite - 50% Vermiculite mix.
4. Powdered rooting hormone.
The Styrofoam cooler was plugged in and left on my outside deck.

This method seemed to work quite well in the spring of 2012. Many cuttings of various varieties grew with only about a 30% loss in cuttings (that never rooted).

When I tried the same method in the spring of 2013, the system was a complete failure. I discovered the heat pad had temperatures that were extremely inconsistent with cold, warm and hot zones. my grape cuttings were either too cold or they baked from being too hot. Only a small area within the cooler was a success with growing & rooted cuttings (Niagara grapes). Apparently the temperature was just right in this small zone within my cooler.

I have since thrown out this heat pad. I am preparing for the spring of 2014 and I am looking for a better quality heat mat to use. Once I get a new heat mat, I am thinking of using a layer of small bubble wrap as a buffer between the mat and the growing medium to help equalize any variations in heat.

Does anyone have any recommendations for a quality heat mat with consistent heat throughout?
Or does anyone have any recommendations on how I can tweak my grape propagation system?

Hi, I've been told by the Iowa State horticulturist to take hardwood cuttings in late Feb. He didn't specify the length . I've been taking these for years now and find about three to five inches works okay. Cut the top straight and the bottom at a slant ( helps to remember which way goes down). tie them in a bundle and place them in a bag with moisten sand and place them in the refrigerator. After the callus forms which would be around the first of April he advises to plant them out in a protected place from the sun, water daily and by the next spring dig them up and plant them in there permanent place in your vineyard. I had very good luck this way and I have also put them in a shaded cold frame with sand and watered twice daily mainly with a hand held sprinkling can and got the leaves wet. It helps to keep the moisture level up with some shallow trays of water too. I have had pretty good luck this way also. Probably about 70 percent rooted this way and 85 percent rooted the other way. It's a lot cheaper this way too.

i AGREE WITH "old lady 59" with the following additions. Use 2-3 eye cuttings of "new growth" or the curent years growth...
Apply 2-3% IBA (rooting hormone) to the burried eye.
cuttings will will root within 80 days usually within 20 days